[anjan_c2007]

The CDI unit of an Activa:-
This unit works seamlessly and silently without showing its fangs for years and years ( OE factory fitted CDI unit has lasted me for two decades since 2003). But after it reaches a certain age in many cases it creates niggles and the user is perplexed as to whether the fault is with the spark plug, ignition coil or elsewhere. The first components be suspected are the spark plug or the carburettor. Thereafter if there's no current supply, the spark plug becomes the prime suspect.

The CDI issue has very distinctive symptoms and can be very easily diagnosed to target its malfunctioning if such issues are faced. An Activa with a malfunctioning CDI unit refuses to start at the start of the day of use. Despite usage of all tricks in the book scooter doesn't start. At times many selfs and at least 40-50 kicks could be required for the engine to fire to life. And then the most important fact is that the machine runs flawlessly throughout the day just requiring a self to get started. And again after resting for 12 plus or more hours, the same symptoms are observed. Sometimes, the user gets fed up in the morning and leaves the Activa back, taking some other mode of transport.



The OE factory fitted CDI unit



The OE factory fitted old (left) seen on its flip side and the aftermarket new Nippon India made CDI units side by side (new one costs Rs 690/-). Even the old rubber fastener had decayed after two decades and is now replaced. But if a replacement of the CDI unit is needed, its advisable to carry the fitted unit as sample to the spares shop, as the company had changed the CDI type during its model life.



"The old order changeth ushering in the new" - the new CDI unit is fitted

Another way of making the old CDI unit is to hit its body a number of times with the plastic head of a screw driver. But we must never hit it so hard so as to damage its plastic enclosure box.

With fitment of the new CDI unit, my Activa requires just half a self to start and it's performance has improved a lot. The enhanced electric supply due to the new CDI unit fitment enhances the spark intensity and also results in better combustion of the air-petrol vapour mix supplied to the engine.

[Aditya]

Honda Activa CDI unit issue | Symptoms and replacement - Post moved to a new thread.

[anjan_c2007]

An update:-
Flawless performance post the fitment of a new CDI unit continues till date, the two wheeler starting with just half a self these days. If parked unused for a few days, it requires a full self to trigger activity through its crankcase, and get going.

Another reason apart from the CDI unit change, is that prior to this self diagnosis of the defective unit by me, the entire fuel line upto the carburettor and all the other electricals were thoroughly checked, tweaked and if necessary cleaned, everyone of them becoming prime suspects for the starting trouble issue in the mornings. Hence, if the other prime suspects are thoroughly checked, found not guilty and acquitted, they usually go gaga with joy and perform well.

Accessing the CDI unit :-

CDI unit is the 'fountain of the electrical setup' and is housed far away from all these other prime suspects and hence escapes detection in a majority of cases. To access it, the two star screws on the flip side (driver's side) at the top of the footboard just below the handlebar have to opened. The front shield housing the battery can then be opened by pulling it forward carefully from just below the headlight. There are two rubber bush mounted fasteners that hold this 'front shield' at the base and these are easily dismounted. The CDI unit is affixed with the rubber strap (as in the image above in OP) and can be detached easily, by disconnecting the OE wiring sockets. To fit the new one, the OE wiring sockets can be gauged and the appropriate slots on the new CDI unit identified which is an easy job. The wiring sockets then flawlessly fit into their new CDI unit slots. After refitting, fastening the rubber belt to secure the CDI unit, the 'front shield' can be refitted by first fitting the two lower fasteners at its base on the lower rubber bushes. It needs a mild downward push to secure itself on the two rubber bushes. After another push at the top, the two star screws atop the footboard, towards the driver's side can be fastened.

Affixed with a new 'fountain of the electrical setup', now the scooter gets a new lease of life and you can Vroooom and Vroooom with joy!